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The burden of proof

Here's an issue that keeps cropping up in the debate about God's existence: where does the burden of proof lie? Do theists have to prove their claim that God exists, or do atheists have to prove their claim that God doesn't exist? Predictably, there's frustration on both sides of the isle – atheists argue that believers are the ones making the claim, therefor the burden of proof lies with them. But theists assert that atheists are making a claim of their own that also must be proved.

Let's start with some basic philosophy: the burden of proof always falls on the person making the affirmative claim. This is logic 101. If your friend Cletus tells you that aliens are visiting Earth, the burden is not on you to disprove his claim – he is holding the affirmative position, and the burden of proof rests solely upon him. In this case, you hold what is called the null hypothesis:

The null hypothesis typically proposes a general or default position, such as that there is no relationship between two measured phenomena... It is typically paired with a second hypothesis, the alternative hypothesis, which asserts a particular relationship between the phenomena.... The alternative need not be the logical negation of the null hypothesis and predicts the results from the experiment if the alternative hypothesis is true. [Wikipedia]

You are not asserting that aliens are not visiting Earth. If you did, you would be making an affirmative claim that demands evidence, and it's impossible to conclusively disprove the notion that aliens are visiting Earth. Instead, you are simply suggesting that your friend must demonstrate his claim to be true, and until that happens you refuse to join him in holding the affirmative position.

As I said, this is logic 101, and no one should be disagreeing at this point. The question is not whether the proof lies with the person in the affirmative – the question, in the debate about God's existence, is whether atheists are in fact making affirmative claims.

The theistic position

Theistic arguments typically rest upon the notion that God's existence is self-evident. For example:

The universe appears designed to be favorable to intelligent life (argument from design)

The mere existence of the universe seems to require a creator (cosmological argument)

If God did not create and design the universe, then how else could we explain it?

Arguments such as the cosmological and design arguments assert that God's existence is essentially tautological. If the universe contains hallmarks of design, it must be designed. If it contains hallmarks of creation, it must have been created.

However, these are arguments from ignorance:

Argument from ignorance, also known as argumentum ad ignorantiam or appeal to ignorance, is an informal logical fallacy. It asserts that a proposition is necessarily true because it has not been proven false (or vice versa). This represents a type of false dichotomy in that it excludes a third option: there is insufficient investigation and the proposition has not yet been proven to be either true or false.[1] In debates, appeals to ignorance are sometimes used to shift the burden of proof. [Wikipedia]

This is a common tactic used by theists: If God didn't create the universe, then how do you explain it? Notice the connection between the null hypothesis and the argument from ignorance: the latter is an attempt to negate the former by positing it as an alternative proposition rather than the default position.

This is compounded by the problem of defining "God": there are many, many conceptualizations of gods. Which, precisely, is the person in the affirmative arguing for? For example, I could argue for the existence of a pantheistic god who is innately intertwined with and inseparable from the universe. I could argue for a deistic god who remains separate from the universe and acted only as a sort of divine watchmaker. Or, I could argue for a theistic god who exists separately from the universe and acts within it. Is God eternal, beyond space and time, omnipotent and omniscient? Some theists, such as Rabbi Harold Kushner, argue that God is not omnipotent. Are there many gods, or one? The more qualities the theist ascribes to God, the more complex their burden of proof becomes.

The atheist position

The atheist does not necessarily claim that a god of some kind does not or cannot exist; rather, per the null hypothesis, the atheist claims that evidence is insufficient to establish the existence of God: that in fact God's existence is not self-evident. Not only are the philosophical proofs of God asserted as arguments from ignorance, but they can be demonstrated as riddled with logical fallacies, such as the cosmological argument's fallacies of equivocation.

When theists are confronted with this argument, they generally resort to conflating the null hypothesis with a sort of neutral agnosticism. However, this distorts the actual meaning of the word agnosticism:

Thomas Henry Huxley, an English biologist, coined the word agnostic in 1869... [he] defined the term: Agnosticism is not a creed but a method, the essence of which lies in the vigorous application of a single principle... Positively the principle may be expressed as in matters of intellect, do not pretend conclusions are certain that are not demonstrated or demonstrable.[Wikipedia]

In other words, agnosticism is a statement about epistemology, or what can be known. Huxley is saying that if a conclusion is not demonstrably true, its truth is unknowable. So, in a sense, we atheists are indeed agnostic about the existence of God, just as we are agnostic about the existence of aliens that visit Earth. However, the use of the term agnostic should not be misconstrued to mean that the null and alternative hypotheses each have an equal probability value.

For example, those of us who don't believe that aliens are visiting Earth are likely aware that we cannot disprove the claim; however, we also believe that it's highly unlikely that aliens are visiting Earth, because there ought to be certain kinds of evidence that they are. In other words, we see not only an absence of evidence, but evidence of absence. This can be related back to a recent post I did on dark matter. Physicists have for years been attempting to directly detect dark matter, with no positive results – instead, they re-adjust their parameters and search again. Some physicists, though, are suggesting that the repeated failure to confirm the existence of dark matter is evidence that it does not exist, and instead we must refine our understanding of gravity.

Atheists assert that if a given conceptualization of God is accurate, we ought to see evidence that it is true. For example, if God regularly intervenes in the natural world through anything from answered prayers to natural disasters, we ought to see evidence for this beyond mere statistical probability. And even if God is merely a creator, we ought to see independently verifiable evidence that objectively reveals this specific conceptualization of God, rather than merely asserting it as tautological in the absence of an alternative hypothesis.

Final words

Theists often attempt to shift the burden of proof by claiming that an atheist must, by default, be asserting an affirmative position that only the material world exists as a matter of ontological truth. But that's not what we're doing. Atheism is a null hypothesis. The existence of God is not self-evident, and the absence of rigorously proved alternative hypotheses for, say, the origin or nature of the universe, is not evidence that God exists by default – to claim as such is an argument from ignorance. The view that the the existence of gods is highly improbable, and that it is more likely that the natural world is all that exists, is the de facto atheist position. This is a valid epistemic position based on the absence of evidence for God's existence. And, per Huxley's original definition of agnosticism, if God does exist but cannot be detected in any independently verifiable way, then we cannot know whether God exists or not – and as I always say, the only thing worse than a god who doesn't exist is a god who might as well not exist.

I'll leave with Richard Dawkins' spectrum of theistic probability, which he published in The God Delusion. I consider myself a "6".

Strong theist. 100 per cent probability of God. In the words of C.G. Jung, 'I do not believe, I know.'

Very high probability but short of 100 per cent. De factotheist. 'I cannot know for certain, but I strongly believe in God and live my life on the assumption that he is there.'

Higher than 50 per cent but not very high. Technically agnostic but leaning towards theism. 'I am very uncertain, but I am inclined to believe in God.'